The scientific issues of this project are focused around four core developmental phenomena of the 18-23 year old period: 1) this period is normatively the highest alcohol consumption interval in the life course;2) toward the end of this interval, for the majority of young adults, a decrease in consumption begins to take place;3) for a higher risk subset of the population, the high consumption pattern continues;and 4) while these critical behavioral shifts are occurring, the neural networks responsible for effortful control and reward response/incentive reactivity are also maturing, albeit at different rates. Three corollary, as yet unanswered questions critical to both social policy about youthful drinking and intervention, are to be addressed: A) To what degree are the changes in drinking behavior taking place over this developmental interval attributable to the maturation of these neural networks?;B) Does heavy alcohol consumption influence the maturation of these networks?;C) How do social environmental reinforcers and prior individual differences in risk mediate or moderate both of these outcomes? During the past 5 years, this project has investigated neurocognitive and functional brain indicators of later problem alcohol use, identifying trajectories of problem use and neural indicators of risk and resilience. This revised continuation project builds on this prior work by extending the investigation into early adulthood and identifying effects of heavy drinking on personality, neurocognition and brain function as well as the interactions between early risk, heavy drinking, and social context (social supports, peer drinking, environmental insults) throughout adolescence and early adulthood. Subjects are participants in the Michigan Longitudinal Study, a high risk for alcohol use disorder family study that has been characterizing temperament, behavioral risk and social context since early childhood and neurocognitive risk since early adolescence. Associated brain function has been studied using fMRI since late adolescence in a subset of these participants. Over the next 5 years, the study will probe the two domains of Effortful Control, and Incentive Reactivity, assessed at the levels of brain function (Regulation/dysregulation of frontostriatal and frontolimbic circuitry and connectivity), neurocognition, and personality. Neurocognitive and personality assessments will continue at 3 year intervals (N= 1456), starting at age 12;a subset of participants (N = 225) will continue to be assessed yearly via fMRI starting at age 18. An important new focus of the imaging work is the interaction between frontal and subcortical processes, to be explored longitudinally using a delayed discounting task, and frontostriatal and frontolimbic functional connectivity analyses. Results will developmentally characterize the relationship between drinking behavior, social environment, and brain function and connectivity change. A special focus is the extent to which drinking behavior lags brain change or leads it, and the role that social environment plays in moderating such change. PUBLIC HEALTH RELEVANCE: This project is likely to promote a more in-depth understanding about the intermediate neural pathways underlying susceptibility to heavy drinking and alcohol use disorder at an age interval when both of these phenomena reach their peak. Results will provide new knowledge of how temperament, behavior, brain networks and social environmental risk interact, influencing stability and change in drinking behavior and brain functional networks at arguably the most critical developmental period for alcohol use in the lifespan. Findings will have implications for early identification, prevention, and early treatment of at risk individuals, as well as those in the early stages of an alcohol abusing career.